1. Field of the Invention
The present invention relates to an apparatus and method for generating an antenna. In particular, the present invention relates to an apparatus and method for generating a fluid antenna.
2. Description of Related Art
Electromagnetic energy can be used in many ways to sense or affect objects from a distance. Radar, for example, is reflected electromagnetic energy used to determine the velocity and location of a targeted object. It is widely used in such applications as aircraft and ship navigation, military reconnaissance, automobile speed checks, and weather observations. Electromagnetic energy may also be used to jam or otherwise interfere with radio frequency transmissions or to affect the radio transmitting equipment itself.
In certain situations, it may be desirable to radiate one or more electromagnetic pulses over an area to sense or affect objects within the area. Generally, as illustrated in FIG. 1, a signal generator 101 generates an electromagnetic pulse, which is radiated by an antenna 103 as an electromagnetic wave 105. Upon encountering an interface, such as an interface between an object 107 and a surrounding medium 109 (e.g., an atmosphere), a portion of the energy of electromagnetic wave 105 is reflected as an electromagnetic wave 111. Reflected electromagnetic wave 111 may then be received by a sensor 113, which analyzes reflected wave 111 to determine various characteristics of object 107.
It is often desirable to deploy such antennas, e.g., antenna 103, during flight. For example, a vehicle approaching an object may deploy an antenna so that electromagnetic energy may be directed toward the object. Conventional antennas generally include rigid or semi-rigid members that may be compactly folded for storage and transport and then unfolded when needed. Alternatively, conventional antennas may be wires that are explosively deployed or deployed by parachutes. A substantial amount of time is often required to deploy such antennas, which results in additional planning to determine the appropriate time to begin deployment so that the antenna will be available when needed. Further, circumstances may arise in which the immediate transmission of electromagnetic energy is desirable. If the antenna has not been deployed, there may not be sufficient time to deploy the antenna and transmit the electromagnetic energy in the desired time frame.
In other implementations, the vehicle from which the antenna is being deployed may be traveling at a very high rate of speed, for example, at a speed greater than the speed of sound. If the medium through which the vehicle is traveling has significant density, such as an atmosphere, considerable forces may act on such conventional antennas when deployed. It may, therefore, be very difficult, if not impossible, for such conventional antennas to be deployed without damage from fast-moving vehicles.
It is also be desirable in certain situations to transmit electromagnetic energy having a broad spectrum of frequencies or to transmit low frequency electromagnetic energy. Generally, longer antennas are capable of transmitting electromagnetic energy more efficiently at lower frequencies than shorter antennas. Such longer antennas are typically capable of transmitting electromagnetic energy having higher frequencies as well. Longer, foldable antennas require more storage space, are typically more complex, generally take longer to unfold, and are typically more susceptible to damage upon deployment.
While there are many deployable antennas well known in the art, considerable room for improvement remains.